This issue of Hematology/Oncology Clinics is guest edited by Dr. A. Koneti Rao and focuses on Disorder of the Platelets. Article titles include: Mechanisms of Platelet Activation and Inhibition, Testing Platelet Function,Clinical Implications of Platelet Genomics and Proteomics, Congenital Thrombocytopenias, Immune Thrombocytopenias, Heparin Induced Thrombocytopenia, and Functional defects: Chronic granulomatous disease (CGD) and beyond.